Classical chemical analytical instruments, such as High-performance Liquid Chromatography (HPLC), Gas Chromatography (GC), Capillary Electrophoresis (CE) and Plasma Atomic Emission Spectrometry (PAES) have been used to assess concentration of ions in an environment. However, these instruments are expensive, not very portable and require considerable preparation and analysis time to assess concentrations, and thus are not suited to being deployed in real time, in situ applications. Such applications include, for example, food quality control in the food industry, nutrient monitoring in the agricultural sector and industrial pollution assessment for environmental monitoring.
In an example, assessment of water quality is important in a range of industries including agronomy, horticulture, waste water management, and nutrient monitoring of freshwater waterways and reservoirs. Examples of water quality assessment in agronomy/horticulture include: nutrient monitoring for a wide range of vegetable crops; hydroponic farming; irrigation water quality analysis; irrigation water discharge security; and soil structure and quality analysis.
Current water quality assessment methods require users to collect samples, send them to a laboratory, and wait several days for the results. This process is time consuming, costly, inefficient and does not allow for real time monitoring of water quality.
While commercial Ion Selective Electrodes (ISEs) have the capacity to provide rapid and quantitative analysis of an ion in solution, these existing ISEs have been limited by their inability to provide accurate readings of mixed ion samples. Ion Selective Electrodes (ISEs) are normally co-reactive which means that one ISE responds to similar analyte ions in solution and many ISEs in an array of ISEs respond to the same analyte ion. Interference from the other undesired analytes, which are similar to the desired one, constitutes one problem faced when ion-selective electrodes are used. In one example, attempts have been made to minimise interference by removing interfering analytes from the solution by chemical precipitations. However, the chemicals used might not be able to remove all the undesired analytes and also can introduce further interference. In another example, to avoid disturbing the natural speciation of the solution using chemicals, analysis can be done using the co-reactive electrode sensor array data directly using computational methods. However, the accuracy of these methods is still far from satisfying the requirements for, say, simultaneous determination of multiple chemical compositions, especially in complex mixtures of ions.
It is therefore desirable to provide a method and/or device that is able to rapidly and reliably assess concentrations of ions in a mixed ion solution.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.